Transistor devices such as field-effect controlled transistor devices are widely used as electronic switches or active rectifier elements in automotive, industrial, or consumer electronic applications. Such transistor devices, which are often referred to as power transistor devices, include a plurality of device cells (transistor cells) that are connected in parallel by having gate nodes of the individual device cells connected to a common gate node, by having drain nodes of the individual device cells connected to a common drain node, and by having source nodes of the individual device cells connected to a common source node.
In such a transistor device the common source node can be formed by a contact layer (metallization layer). This contact layer can be soldered to an electrode layer, which may be part of an electrical connector, a printed circuit board (PCB), or the like. Soldering the contact layer to the electrode layer includes forming a solder layer on the contact layer, wherein the solder layer electrically connects the contact layer with the electrode layer. This solder layer may include voids. Those voids locally increase the electrical resistance between and the thermal resistance between the contact layer and the electrode layer. A local increase of the thermal resistance may cause the transistor device to overheat in regions below the void.
There is therefore a need for a transistor device that is robust against imperfections, such as voids, of a solder layer.